Dynamic Characteristics of Coarse Aggregates within Epoxy Asphalt Mixture during Superpave Gyratory Compaction

2019 ◽  
Vol 48 (6) ◽  
pp. 20180723 ◽  
Author(s):  
Xiang-fei Zhang ◽  
Zhen-dong Qian ◽  
Dong Zheng ◽  
Leilei Chen
Keyword(s):  
Dynamic Characteristics ◽  
Asphalt Mixture ◽  
Coarse Aggregates ◽  
Epoxy Asphalt ◽  
Gyratory Compaction

scholarly journals Experimental and Numerical Analysis on Mesoscale Mechanical Behavior of Coarse Aggregates in the Asphalt Mixture during Gyratory Compaction

Processes ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 47
Author(s):  
De Zhang ◽  
Zhiqiang Cheng ◽  
Dajiang Geng ◽  
Shengjia Xie ◽  
Tao Wang
Keyword(s):  
Contact Stress ◽  
Positive Impact ◽  
Asphalt Mixture ◽  
Contact Forces ◽  
Normal Contact ◽  
Coarse Aggregates ◽  
Stress Rotation ◽  
Gyratory Compaction ◽  
Internal Angle ◽  
Pavement Construction

Compaction is a critical step in asphalt pavement construction. The objective of this study is to analyze the mesoscale mechanical behaviors of coarse aggregates in asphalt mixtures during gyratory compaction through experiments and numerical simulation using the Discrete Element Method (DEM). A novel granular sensor (SmartRock) was embedded in an asphalt mixture specimen to collect compaction response data, including acceleration, stress, rotation angle and temperature. Moreover, the irregularly shaped coarse aggregates were regenerated in the DEM model, and numerical simulations were conducted to analyze the evolution of aggregate interaction characteristics. The findings are as follows: (1) the measured contact stress between particles changes periodically during gyratory compaction, and the amplitude of stress tends to be stable with the increase of compaction cycles; (2) the contact stress of particles is influenced by the shape of aggregates: flat-shaped particles are subjected to greater stress than angular, fractured or elongated particles; (3) the proportion of strong contacts among particles is high in the initial gyratory compaction stage, then decreases as the number of gyratory compactions grows, the contacts among particles tending to homogenize; (4) during initial gyratory compactions, the normal contact forces form a vertical distribution due to the aggregates’ gravity accumulation. The isotropic distribution of contact forces increases locally in the loading direction along the axis with a calibrated internal angle orientation (1.25°) in the earlier cyclic loading stage, then the local strong contacts decrease in the later stage, while the strength of the force chains in other directions increase. The anisotropy of aggregate contact force networks tends to weaken. In other words, kneading and shearing action during gyratory compaction have a positive impact on the homogenization and isotropy of asphalt mixture contact forces.

A Hybrid Model to Predict the Gyratory Compaction of Hot Mixed Asphalt

2019 ◽  
Author(s):  
Teng Man
Keyword(s):  
Hybrid Model ◽  
Asphalt Binder ◽  
Asphalt Mixture ◽  
Aggregate Size ◽  
Asphalt Mixtures ◽  
Compaction Process ◽  
Particle Rearrangement ◽  
Compaction Behavior ◽  
Grain Size Distributions ◽  
Gyratory Compaction

The compaction of asphalt mixture is crucial to the mechanical properties and the maintenance of the pavement. However, the mix design, which based on the compaction properties, remains largely on empirical data. We found difficulties to relate the aggregate size distribution and the asphalt binder properties to the compaction behavior in both the field and laboratory compaction of asphalt mixtures. In this paper, we would like to propose a simple hybrid model to predict the compaction of asphalt mixtures. In this model, we divided the compaction process into two mechanisms: (i) visco-plastic deformation of an ordered thickly-coated granular assembly, and (ii) the transition from an ordered system to a disordered system due to particle rearrangement. This model could take into account both the viscous properties of the asphalt binder and grain size distributions of the aggregates. Additionally, we suggest to use the discrete element method to understand the particle rearrangement during the compaction process. This model is calibrated based on the SuperPave gyratory compaction tests in the pavement lab. In the end, we compared the model results to experimental data to show that this model prediction had a good agreement with the experiments, thus, had great potentials to be implemented to improve the design of asphalt mixtures.

scholarly journals Evaluation of the Effects of Filler Fineness on the Properties of an Epoxy Asphalt Mixture

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2003
Author(s):  
Wei Xu ◽  
Jintao Wei ◽  
Zhengxiong Chen ◽  
Feng Wang ◽  
Jian Zhao
Keyword(s):  
Particle Size ◽  
Average Particle Size ◽  
Asphalt Mixture ◽  
Average Particle ◽  
Fine Dust ◽  
Bonding Structure ◽  
Epoxy Asphalt ◽  
Mineral Powder ◽  
Marshall Stability ◽  
Mixture Sample

The type and fineness of a filler significantly affect the performance of an asphalt mixture. There is a lack of specific research on the effects of filler fineness and dust from aggregates on the properties of epoxy asphalt (EA) mixtures. The effects of aggregate dust and mineral powder on the properties of an EA mixture were evaluated. These filler were tested to determine their fineness, specific surface area and mineral composition. The effects of these fillers on the EA mastic sample and mixture were evaluated. The morphology of the EA mastic samples was analyzed using scanning electron microscopy (SEM). The effects of the fillers on the Marshall stability, tensile strength and fatigue performance of the EA mixture were evaluated. The dust from the aggregates exhibited an even particle size distribution, and its average particle size was approximately 20% of that of the mineral powder. The SEM microanalysis showed that the EA mastic sample containing relatively fine dust formed a tight and dense interfacial bonding structure with the aggregate. The EA mixture sample containing filler composed of dust from aggregate had a significantly higher strength and longer fatigue life than that of the EA sample containing filler composed of mineral powder.

scholarly journals Chemical and Physical Properties of Limestone Powder as a Potential Microfiller of Polymer Composites

2017 ◽  
Vol 63 (2) ◽  
pp. 67-78 ◽  
Author(s):  
M. Kępniak ◽  
P. Woyciechowski ◽  
W. Franus
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Physical Properties ◽  
Polymer Composites ◽  
Asphalt Mixture ◽  
Limestone Powder ◽  
Coarse Aggregates ◽  
Mineral Powder ◽  
Materials Used ◽  
Scanning Electron

Abstract The preliminary stage of asphalt mixture production involves the drying and dedusting of coarse aggregates. The most common types of coarse aggregates used are limestone and basalt. In the process of drying and dedusting the dryer filter accumulates large quantities of waste in the form of mineral powder. This paper introduces an investigation into limestone powder waste as a potential microfiller of polymer composites. Physical characteristics such as the granulation the of powder collected from the filter - in terms of the season of its collection and the type of input materials used - were analysed. A scanning electron microscope (SEM) was used for the investigation described within this paper. The obtained results were compared against those of other materials which can be used as polymer composites microfillers.

scholarly journals A Comprehensive Evaluation of Rejuvenator on Mechanical Properties, Durability, and Dynamic Characteristics of Artificially Aged Asphalt Mixture

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1554 ◽  
Author(s):  
Pan Pan ◽  
Yi Kuang ◽  
Xiaodi Hu ◽  
Xiao Zhang
Keyword(s):  
Mechanical Properties ◽  
Dynamic Characteristics ◽  
Comprehensive Evaluation ◽  
Asphalt Binder ◽  
Asphalt Mixture ◽  
Physical Property ◽  
Fatigue Property ◽  
Physical Test ◽  
Aged Asphalt

In this study, the aged asphalt binder and mixture were laboratory prepared through short-term ageing testing and long-term ageing testing. Firstly, the effect of rejuvenator on physical properties of aged asphalt binders was investigated. In addition, a series of laboratory tests were performed to evaluate the influence of ageing and rejuvenator content on the mechanical properties, durability and dynamic characteristics of asphalt mixtures. Physical test results of asphalt binder testified that rejuvenator used can efficiently recover the aged asphalt binder. However, the effect of ageing and rejuvenator content exhibits different trends depending on the physical property tests conducted. Moreover, artificially aged asphalt mixture with rejuvenator has better ability to resist moisture damage and ravelling. In addition, the ITSR value is more suitable to evaluate the moisture susceptibility for asphalt recycling. Although rejuvenator improves the thermal cracking resistance and fatigue property of aged asphalt mixture, rejuvenated mixture shows greater modulus and inferior ability to resist reflective cracking than the unaged mixture. Moreover, rejuvenated mixture shows less dependence on frequency at high temperature regions and stronger dependence at low temperature regions compared to unaged and long-term aged mixtures.

scholarly journals Laboratory Evaluation of the Use of Florida Washed Shell in Open-Graded Asphalt Mixtures

Materials ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 7060
Author(s):  
Mohammad Alharthai ◽  
Qing Lu ◽  
Ahmed Elnihum ◽  
Asad Elmagarhe
Keyword(s):  
Tensile Strength ◽  
Asphalt Mixture ◽  
Asphalt Mixtures ◽  
Indirect Tensile Strength ◽  
Laboratory Evaluation ◽  
Void Content ◽  
Coarse Aggregates ◽  
Significant Difference ◽  
Indirect Tensile ◽  
Marshall Stability

This study investigates the substitution of conventional aggregate with a Florida washed shell in open-graded asphalt mixtures and evaluates the optimal substitution percentage in aggregate gradations of various nominal maximum aggregate sizes (NMASs) (i.e., 4.75, 9.5, and 12.5 mm). Laboratory experiments were performed on open-graded asphalt mixture specimens with the coarse aggregate of sizes between 2.36 and 12.5 mm being replaced by the Florida washed shell at various percentages (0, 15, 30, 45, and 100%). Specimen properties relevant to the performance of open-graded asphalt mixtures in the field were tested, evaluated, and compared. Specifically, a Marshall stability test, Cantabro test, indirect tensile strength test, air void content test, and permeability test were conducted to evaluate the strength, resistance to raveling, cracking resistance, void content, and permeability of open-graded asphalt mixtures. The results show that there is no significant difference in the Marshall stability and indirect tensile strength when the coarse aggregates are replaced with Florida washed shell. This study also found that the optimum percentages of Florida washed shell in open-graded asphalt mixture were 15, 30, and 45% for 12.5, 9.5, and 4.75 mm NMAS gradations, respectively.

scholarly journals The use of Crushed Waste Glass as a Partial Replacement of Fine Aggregates in Asphalt Concrete Mixtures (Glassphalt)

2021 ◽  
pp. 1-10
Author(s):  
Gbadamosi Aderemi Tobi ◽  
Ogunsuyi Raphael Abidemi ◽  
Ojo Meshach Felix
Keyword(s):  
Asphalt Binder ◽  
Asphalt Mixture ◽  
Waste Glass ◽  
Partial Replacement ◽  
Glass Waste ◽  
Coarse Aggregates ◽  
Rapid Economic Growth ◽  
Marshall Test ◽  
Bitumen Content ◽  
Asphalt Mix

With the rapid economic growth and continuously increased consumption, a large amount of glass waste materials is generated; this study investigated the effect of crushed waste glass as filler and also as an aggregate in the asphalt binder course. It compares the glassphalt mix with the specification range at different percentages to meet specifications limit according to Nigeria roads and bridges reverse book of 1997 Waste glass are cleaned and crushed from the glass bottles and added to the asphalt as a filler and as a replacement for coarse aggregates, the marshal method is used to determine the optimum bitumen content and evaluate the properties of the asphalt mix. However, 24 samples were prepared in total, 12 samples each for the asphalt mix used to determine the optimum bitumen content and the other 12 samples for the glassphalt mix used to find out the effect of adding the different percentages of crushed waste glass to the asphalt mixture. The Marshall test carried out on the asphalt mixtures showed that the optimum bitumen content of bitumen was found out to be 6.2% of the asphalt mix by weight. Also, Marshall Test carried out on the glassphalt mix showed the optimum percentage of glass used in the binder course of the weights of aggregates in the asphalt mix. The result of this experiment is been checked to be consistent with the Nigeria road and bridges reverse book of 1997, i.e. Marshall Stability, flow, bulk density, and air voids.

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